1. Field of the Invention
This invention relates generally to concentrating evaporators of the closed evaporating chamber type and more particularly to methods and apparatus for gradually evaporating liquids to separate solid substances therein to leave a residue of the substances.
2. Brief Description of the Prior Art
Various methods have been used to separate liquids from solid substances, particularly, in the field of medicine, where it is often desirable to analyze various chemical substances. For example, it is often necessary to analyze various constituents found in blood for determining the presence of diseases in persons from whom blood is drawn or, in experimental medicine, for the purpose of analyzing antibodies found in blood, plasma, or serum to develop serums for various diseases. There are, of course, many other reasons for analyzing constituents found in blood, plasma, urine, and the like or to identify various substances found in different medicines and other chemicals. It is often necessary to prepare dry substances for analysis although they may be initially contained in a liquid.
Known methods of separating solid substances from liquids containing such substances include centrifuging the liquids; placing the liquids in ovens to evaporate the liquid; filtering the liquids to collect constituents therein in a filter media; and applying subatmospheric pressure to the liquid to cause it to evaporate thereby leaving a residue of the solid substances contained in the liquid.
While there are advantages and disadvantages to each of the known methods, it is frequently desirable to separate the liquids from the solids by evaporation. One type of apparatus currently available is a vortex evaporator. This apparatus can evaporate liquids by vacuum from individual test tubes that have been shaken in a hot water bath. However, it is desirable to be able to evaporate liquids from several test tubes simultaneously and to control "bumping" of the liquid in the test tubes. This so called bumping results from sudden boiling of the liquid, such as occurs during rapid application of vacuum, which forms bubbles in the liquid and causes the liquid to boil over or spray from the test tubes. Bumping is undesirable since it results in a loss of control of the substances to be analyzed.
Recently developed medical techniques of analysis have made it desirable to be able to obtain several dry residues simultaneously and to be able to selectively cool, heat, or agitate the liquids containing the solid substances. In addition, it is sometimes desirable to mix certain chemicals with the liquids prior to evaporation and to add certain chemicals to the residues after evaporation.
Accordingly, it is an object of this invention to provide a method and apparatus for evaporating liquids to separate solid substances contained therein, without bumping, and to evaporate more than one specimen of a liquid at any one time. It is a further object of this invention to provide additional methods and means for use in connection with the evaporation apparatus such as cooling all or a portion of the specimens being evaporated, heating all or a portion of the specimens being evaporated, and agitating the liquid during evaporation thereof to aid in such evaporation. A still further object is to provide means for subjecting the specimens to be evaporated to an inert gas such as nitrogen rather than to earth atmosphere to prevent contamination of the residue left in the test tubes following evaporation of the liquid.